Converted to Manual Brakes-spongy pedal

[ADOBOMiata]

Hey guys,

So I have a 1994 M- Edition shell with ABS brakes. All the lines were deleted, module, except the brake booster.

I changed the brake lines all to stainless steel brakes, NB1 Calipers (front & rear) & Brackets, 1.8 slotted rotors/pads (for a 94), Manual 1.6 brake master cylinder.

I bled the system by doing the "pump and crack bleeder valve" method. I bled the system by starting with the LEFT REAR, then RIGHT REAR, RIGHT FRONT, then LEFT FRONT. After bleeding it for awhile (making sure there are new fluid coming out and clean streams) the pedal still feels a bit spongy.. Should I keep bleeding the system or do I need to change a component?..

Couple things that may be the problem:
-Worn/internally/weak leaking MC (but was working fine from the 92)
-wrong booster?
-possible leak? (I dont see any..)
-too much air in the system


I did not bench bleed the master cylinder... so air is a factor...

[— kung fu jesus —]

If you have any doubt regarding the condition of the master cylinder, replace it.

I have had an MC fail when I opened the system because the extended stroke from repeated bleeding exposed a worn bore. Bench bleeding helps to a certain degree, but in this case I don't think it is helpful to remove.

I have also had air trapped in a system that, quite frankly, just needed time to work towards an end.

If you have leak, you should inspect all the connections, dry them, put tissue paper on them. The paper is extremely thirsty and will draw in even minute amounts immediately.

[smy0003]

When you bleed, only push the pedal as far you would to normally brake. Pushing it to the floor can stress the MC as per what kung fu said.
I'd replace the MC, just had the clutch MC fail on me the other day and that was bad enough, I wouldn't take any chances with the brake MC.

[Rogue]

I always have my assistant give a full stroke….If it fails, then I replace it because it was failing anyway.
Better to replace in the shop, than find out running flat out into turn 2.

After replacing all the lines etc, I'd bleed it, drive it, and rebleed.
So what Booster and which proportioning valve?
ABS valves have much more rear bias.

How are your flairs?

[ADOBOMiata]

Currently, im using the 94 m-edition booster and the 92 MC. Im going to purchase a 94 non-abs mc after work. Is there a difference between the boosters? I have my 92 1.6 booster just in case... Everything that was on the (92) 1.6.. I transferred over.

[Rogue]

I believe 1990-2000 (non-ABS) master/booster are the same, but 1.6 cars do have a different feel.
If you transfer all the '92 system then I would look for a leaking flair or a failing master.
What fluid are you using?

[ADOBOMiata]

regular dot 3 fluid. Should I get a the wilwood proportion valve?

I'll check the flares. That "tissue" method King fu mentioned sounds like a good idea.

[ADOBOMiata]

I used the ABS brake booster. Is that a factor? When I took a look at both, they looked nearly identical...

[ADOBOMiata]

The 1.6 brake pedal feels like a brick.

[NCGreasemonkey]

Just M2C! When I bleed a system I use the one push method. Get a clear clean bottle. Put about a 1/4 of brake fluid in it. Clear line that fits the bleeder nipple. Drop the line into the bottle below the fluid level. Get a buddy, that you know has a good brain cell, and when you open the bleeder have him push the pedal to the floor and hold it till you tighten. You will see bubbles at all wheels while you burp the clear hose. But you should get clean fluid when she is bled.I also do RR, LR, RF and LF. Furthest to closest. Again, just my 2 cents!

Quote from a late old-school wrench-turner: " A car that won't crank won't kill nobody. A car that won't stop WILL!"

[— kung fu jesus —]

^ Good advice. I usually have to remind my HPDE students that I could care less what they do to make their cars faster, as long as it stops when they need it the most.

My wife knows the drill for bleeding brakes. I have had mixed results using a Motive bleeder on Miatas. On my BMWs, the Motive works fantastic.

[ADOBOMiata]

I did the LR RR RF LF method, only because the furthest brake line that travels is actually the driver rear... I know that furthest to closet method works on a lot of cars though .

[Rogue]

Should I get a the wilwood proportion valve?

Which proportion valve are you using now?
Also, I would switch to the Non-ABS booster.

[NCGreasemonkey]

I did the LR RR RF LF method, only because the furthest brake line that travels is actually the driver rear... I know that furthest to closet method works on a lot of cars though .

You are right on our cars. Forgot bout our junction block at the RR.

<sings to self> ' Conjunction junction. Whats our function.' AO will get this one... LOL

[ADOBOMiata]

I am using the stock 1.6 so far.